Switchgear

ABSTRACT

The instrumentation transformers  6   a  to  6   d  and  7   a  to  7   f  for measuring the voltage of the main circuit are arranged within the container  15   b  located in the midst of the containers  15   a  to  15   c.  In the present invention, the containers  15   a  and  15   b  are linked by the insulating tube  21   a  and the primary-side lead lines  49  and  53  connected electrically to the primary-side terminal of the instrumentation transformers  6   a  and  7   a  are made routed from the container  15   b  through the insulating tube  21   a  to the container  15   a,  and the containers  15   b  and  15   c  are linked by the insulating tube  21   b  and the primary-side lead lines  51  and  55  connected electrically to the primary-side terminal of the instrumentation transformers  6   d  and  7   e  are made routed from the container  15   b  through the insulating tube  21   b  to the container  15   c.

This is a continuation of application Ser. No. 09/948,759, filed Sep. 10, 2001, now U.S. Pat. No. 6,459,569 the disclosure which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a substation component for the power generator installed in the power plants such as thermal electric power plants, nuclear power plants and hydro-electric power plants, especially to a switchgear installed on the main circuit from the generators to the transformers.

As for the switchgear installed on the main circuit from the generators to the transformers, for example, what is well known is disclosed in Japanese Patent Laid-Open Number 61-1218 (1986). The switchgear disclosed in this document is composed so that the components for the individual phases are separated and the switchgears are contained in the individual exterior covering, respectively. The upper-side of the exterior covering containing the switchgear is connected through the exterior covering containing the connecting bus tie to the exterior covering containing the disconnecting switch in step-wise configuration.

In this kind of conventional switchgear, the contact makers of the breaker part of the disconnecting switch are made contact to and leave from each other in responsive to the voltage value in the main circuit. In order to measure the voltage value in the main circuit, plural instrumentation transformers are installed at the switchgears. Those instrumentation transformers are installed in separate containers other than the containers containing the breaker part of the disconnecting switch.

In recent years, many efforts are made for integrating components into a unified and composite unit in order to downsize the switchgears and reduce their cost. Along with this trend, there arises strong request to accommodate plural instrumentation transformers in the container including the breaker part of the disconnecting switches. However, there are still unsolved problems regarding the method for the layout of plural instrumentation transformers in three containers arranged together.

SUMMARY OF THE INVENTION

A major object of the present invention is to provide a switchgear enabling to increase the working efficiency for the installation operation of the instrumentation transformers into the containers and the withdrawal operation of the instrumentation transformers from the containers.

The present invention is characterized by such an arrangement of plural instrumentation transformers for measuring the voltage in the main circuit as located within the container in the midst of containers arranged together.

According to the above described embodiment, as plural instrumentation transformers are arranged within the container located in the midst of the center among the containers arranged together, the installation operation of the instrumentation transformers into the containers and the withdrawal operation of the instrumentation transformers 6 a to 6 d from the containers may be applied only to the container 15 b, and the installation and withdrawal operation at the other containers may be done simply by wiring the primary-side lead lines. Owing to this configuration, the work load and work time for the installation operation of the instrumentation transformers 6 a to 6 d into the containers and the withdrawal operation the instrumentation transformers 6 a to 6 d from the containers can be reduced to a large extent.

According to the present invention, it is easy to route the primary-side lead line of the instrumentation transformer from the container located at the center to the containers located at both ends. That is, in case that the instrumentation transformers are installed in the containers located at both ends, there occurs a part in which a couple of primary-side lead lines for the instrumentation transformers are required to be routed. As it is necessary to establish an enough insulation distance between two lead lines in this configuration, the structure of routing the primary-side lead lines may be complicated or the container may be upsized. In contrast, in this invention, as plural instrumentation transformers are arranged within the container located in the midst among the containers, the primary-side lead lines for the instrumentation transformers can be accommodated by a single cable extended from the container located in the midst to the containers located at both ends. Thus, it will be appreciated that the complexity in the routing configuration for the primary-side lead lines and the up sizing of the containers can be reduced.

A couple of coadjacent containers among three containers arranged together are linked by an insulating tube. The primary-side lead line of the instrumentation transformer corresponding to the phase for the containers located at both ends of three containers arranged together is made routed from the container located in the midst among three containers through the insulating tube to the corresponding container located at one of both ends of containers. The reason why the insulation tube is used for linking the containers is to prevent the cyclic current from flowing between the containers.

A breaker part of the disconnecting switch for disconnecting electrically the main circuit is installed at the individual containers arranged together. The breaker part is insulated by the insulating gas such as sulfur hexafluoride, and has a contact makers operated by the manipulator so as to contact to and leave from each other. A switching part of the disconnecting switch, a switching part of the earthing switch and an arrestor, connected electrically to the main circuit, are arranged in three containers arranged together, individually.

The height of the container located in the midst among three containers arranged together is made larger than the height of the other containers in order to establish an enough insulation distance between plural instrumentation transformers and the other components. The primary-side of plural instrumentation transformers is configured with open-delta connection or star connection. The plural instrumentation transformers are supported so as to be suspended down from the ceiling board installed above the container. The arresters are also supported so as to be suspended down from the ceiling board installed above the container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional drawing illustrating the structure of the switchgear as the first embodiment of the present invention.

FIG. 2 is a cut-away drawing at the line II—II of FIG. 1.

FIG. 3 is a cut-away drawing at the line III—III of FIG. 1.

FIG. 4 is a three-phase connection diagram of the switchgear as the first embodiment of the present invention.

FIG. 5 is a cross-sectional drawing illustrating the structure of the switchgear as the second embodiment of the present invention.

FIG. 6 is a cut-away drawing at the line III—III of FIG. 5.

FIG. 7 is a three-phase connection diagram of the switchgear as the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

By referring to attached figures, the embodiment of the present invention is disclosed.

FIG. 4 shows a three-phase connection diagram of the switchgear in the first embodiment of the present invention. The switchgear of this embodiment is a substation component for the power generator installed in the power plants such as thermal electric power plants, nuclear power plants and hydro-electric power plants, which is used for breaking the heavy current in the main circuit from the power generator to the transformers. This switchgear comprises separated components for the individual phases, U-phase, V-phase and W-phase, respectively.

Incidentally, in the hypo-description, in case where the arrangements of the phases of three are the same, in order to avoid reduplicated description, any one of the phases of three (the U-phase in the hypo-description on the present embodiments) is typically explained. Corresponding reference characters of the other phases are shown in parenthesis, and the explanation of there arrangements is omitted.

A component 1 a (1 b, 1 c) in the figure is a switchgear installed in the U-phase (V-phase, W-phase) circuit. The switchgear 1 a (1 b, 1 c) is used for breaking electrically the current flow in the U-phase (V-phase, W-phase).

The disconnecting switch 2 a (2 b, 2 c) is connected to the transformer side of the switch gear 1 a (1 b, 1 c). The disconnecting switch 2 a (2 b, 2 c) isolates electrically the U-phase circuit into the generator-side circuit and the transformer-side circuit. The generator-side circuit is a circuit located between the switchgear 1 a (1 b, 1 c) and the power generator, and corresponds to the circuit including the switchgear 1 a (1 b, 1 c). The transformer-side circuit is a circuit located between the switchgear 1 a (1 b, 1 c) and the transformer, and corresponds to the circuit excluding the switchgear 1 a (1 b, 1 c).

The earthing switch 3 a (3 b, 3 c) and the arrester 4 a (4 b, 4 c) are connected electrically to the transformer-side of the disconnecting switch 2 a (2 b, 2 c). The earthing switch 3 a (3 b, 3 c) is used for reducing the circuit voltage at the transformer-side down to the earthing electric potential and one of its terminal is grounded. The arrester 4 a (4 b, 4 c) is used for regulating the overvoltage transferred to the circuit for U-phase (V-phase, W-phase), and its one terminal is grounded.

The earthing switch 5 a (5 b, 5 c) is connected electrically to the transformer-side of the disconnecting switch 1 a (1 b, 1 c). The earthing switch 5 a (5 b, 5 c) is used for reducing the circuit voltage at the generator-side down to the earthing electric potential and one of its terminal is grounded.

One terminal of the primary side of the instrumentation transformer 6 a is connected electrically to the generator-side of the disconnecting switch 1 a. The other terminal of the primary side of the instrumentation transformer 6 b and one of the primary side of the instrumentation transformer 6 c are connected electrically to the generation-side of the disconnecting switch 1 b. The other terminal of the primary side of the instrumentation transformer 6 d is connected electrically to the generation-side of the disconnecting switch 1 c.

The other terminal of the primary side of the instrumentation transformer 6 a is connected electrically in series connection to one terminal of the primary side of the instrumentation transformer 6 b. The other terminal of the primary side of the instrumentation transformer 6 c is connected electrically in series connection to one terminal of the primary side of the instrumentation transformer 6 d.

The instrumentation transformers 6 a to 6 d are used for measuring the circuit voltage of U-phase to W-phase, and are composed with open-delta connection.

Though not shown in this figure, a feeding disconnecting switch is connected electrically to the generator-side of the disconnecting switches 1 a to 1 c. The instrumentation transformers for the disconnecting switches 2 a to 2 c are connected to the transformer-side of the disconnecting switches 1 a to 1 c.

FIGS. 1 to 3 illustrate the structure of the switchgear implemented with the three-phase connection diagram shown in FIG. 4. A component 10 in the figure is a base pedestal. A storage space is located above the base pedestal 10. Link mechanism parts 12 a to 12 c are contained in the storage space 13, which are connected mechanically through the coupling rod 11 to the manipulator (not shown). A manipulator box 14 is installed on the top and edge of the base pedestal 10 and at one end side of the storage space 13. The manipulator is used for making the contact makers of the disconnecting parts of the disconnecting switches 1 a to 1 c contacted and released on the block. The manipulator box 14 is taller than the storage space 13.

Containers 15 a to 15 c are arranged in the extended direction of the coupling rod 11 above the storage space 13. The width of the individual containers 15 a to 15 c is defined to be identical to each other, and the depth of the individual containers 15 a to 15 c is defined to be identical to each other. Its width is smaller than its depth. The width of the container is defined as the dimension of the container measured in the extended direction of the coupling rod 11. The depth of the container is defined as the dimension of the container measured in the vertical direction with respect to the extended direction of the coupling rod 11. The height of the container 15 a is defined to be the same as the height of the container 15 c. The height of the container 15 b is defined to be higher than the height of the containers 15 a and 15 c.

The container 15 a (15 b, 15 c) is composed of a base plate 16 a (16 b, 16 c), a side wall 17 a (17 b, 17 c) and a roof 18 a (18 b, 18 c), and thus forms a gable-roof shaped box. The container 15 a (15 b, 15 c) is made of metal, and made grounded. A gable-roof shape is such a shape of roof as a couple of plates are coupled to each other and as its side projection looks like “”, one of Japanese Hiragana characters. A gable-roof shaped box means a box having a gable roof.

A ceiling board 19 a (19 b, 19 c) is installed at the roof side 18 a (18 b, 18 c) of the side wall 17 a (17 b, 17 c). The ceiling board 19 a (19 b, 19 c) is used for supporting the pendant instrument transformer and arrestor as described later. A container box 20 a (20 b, 20 c) is installed below the under surface of the base plate 16 a (16 b, 16 c). The container box 20 a (20 b, 20 c) is used for containing the link mechanism 12 a (12 b, 12 c) extended down below the base plate 16 a (16 b, 16 c).

An insulating tube 21 a for coupling between the container 15 a and the container 15 b is installed between the side wall 17 a and the side wall 17 b. An insulating tube 21 b for coupling between the container 15 b and the container 15 c is installed between the side wall 17 b and the side wall 17 c. The insulating tubes 21 a ad 21 b are used as wiring ducts for routing the primary side lead wires for the instrumentation transformer to be described later, from the container 15 b to the containers 15 a and 15 c.

The breaker part 22 a (22 b, 22 c) of the disconnecting switch 1 a (1 b, 1 c) is installed within the container 15 a (15 b, 15). The breaker part 22 a (22 b, 22 c) is enclosed by the main circuit conductor 23 a (23 b, 23 c), the main circuit conductor 24 a (24 b, 24 c) and the insulating member 25 a (25 b, 25 c), which is formed by arranging the switching mechanism part 26 a (26 b, 26 c) at the part where the insulating gas such as sulfur hexafluoride (SF6) are filled.

The main circuit conductor 24 a (24 b, 24 c) and the main circuit conductor 24 a (24 b, 24 c) are cylindrical members having electric conductivity. The main circuit conductor 24 a (24 b, 24 c) is insulated and supported by the insulating and supporting member 27 a (27 b, 27 c) fixed at the base plate 16 a (16 b, 16 c). The main circuit conductor 24 a (24 b, 24 c) is insulated and supported by the insulating and supporting member 28 a (28 b, 28 c) fixed at the base plate 16 a (16 b, 16 c).

The insulating member 25 a (25 b, 25 c) is a cylindrical member formed between the main circuit conductor 23 a (23 b, 23 c) and the main circuit conductor 24 a (24 b, 24 c), which is used for insulating electrically the main circuit conductor 23 a (23 b, 23 c) from the main circuit conductor 24 a (24 b, 24 c), and vice versa.

The switching mechanism part 26 a (26 b, 26 c) is composed of the fixed switching mechanism part 29 a (29 b, 29 c) and the movable switching mechanism part 30 a (30 b, 30 c). The fixed switching mechanism part 29 a (29 b, 29 c) is fixed on the surface of the flange standing out from the peripheral surface of the breaker part 23 a (23 b, 23 c) to its inside in the radial direction, and a stick and fixed contact maker is installed on its central axis. The movable switching mechanism part 30 a (30 b, 30 c) is fixed on the surface of the flange standing out from the peripheral surface of the breaker part 24 a (24 b, 24 c) to its inside in the radial direction so as to face in an opposed position to the fixed switching mechanism part 29 a (29 b, 29 c). At the center part of the movable switching mechanism part 30 a (30 b, 30 c), a movable contact maker is installed so as to be enable to contact to and leave from the fixed contact maker of the fixed switching mechanism part 29 a (29 b, 29 c).

One side of the link mechanism 12 a (12 b, 12 c) is connected mechanically to the movable contact maker of the movable switching mechanism part 30 a (30 b, 30 c) at its opposite side to the fixed switching mechanism part 29 a (29 b, 29 c). The link mechanism 12 a (12 b, 12 c) is formed as a unit of mechanical components coupled mechanically to one another such as insulating rod, revolving shaft lever and operation rod, which reaches the inside of the current-carrying conductor 27 a (27 b, 27 c) from the inside of the container box 20 a (20 b, 20 c) through the hollow part formed in the insulating and supporting member 28 a (28 b, 28 c). Hexafluoride (SF6) gas as the insulating gas is filled in the hollow part of the insulating and supporting member 28 a (28 b, 28 c) and the inside of the container box 20 a (20 b, 20 c).

The switchgear 1 a (1 b, 1 c) in this embodiment is configured as a puffer so that the arc generated when opening the movable contact maker from the fixed contact maker may be extinguished by spraying the compressed hexafluoride gas used as insulating material at the breaker part 22 a (22 b, 22 c).

The switching part 31 a (31 b, 31 c) of the disconnecting switch 2 a (2 b, 2 c) is placed on the coaxial line shared by the breaker part 22 a (22 b, 22 c) of the disconnecting switch 1 a (1 b, 1 c). The switching part 31 a (31 b, 31 c) is formed by arranging the switching mechanism part 34 a (34 b, 34 c) at the area enclosed by the main circuit conductor 24 a (24 b, 24 c), the main circuit conductor 32 a (32 b, 32 c) and the insulating member 25 a (25 b, 25 c). The switching mechanism part 34 a (34 b, 34 c) is insulated by air not like the switching mechanism part 26 a (26 b, 26 c) of the breaker part 22 a (22 b, 22 c).

The main circuit conductor 32 a (32 b, 32 c) is a conductive member shaped in a cylinder. The main circuit conductor 32 a (32 b, 32 c) is insulated and supported by the insulation and supporting member 35 a (35 b, 35 c) fixed at the base plate 16 a (16 b, 16 c). The insulating member 33 a (33 b, 33 c) is a member shaped in a cylinder installed between the main circuit conductor 24 a (24 b, 24 c) and the main circuit conductor 32 a (32 b, 32 c), and is used for insulating electrically between the main circuit conductor 24 a (24 b, 24 c) and the main circuit conductor 32 a (32 b, 32 c).

The switching mechanism part 34 a (34 b, 34 c) is composed of the fixed switching mechanism part 36 a (36 b, 36 c) and the movable switching mechanism part 37 a (37 b, 37 c). The fixed switching mechanism part 36 a (36 b, 36 c) is connected electrically to the main circuit conductor 24 a (24 b, 24 c) and has a fixed contact maker. The movable switching mechanism part 37 a (37 b, 37 c) is on the surface of the flange standing out from the peripheral surface of the main circuit conductor 32 a (32 b, 32 c) to its inside in the radial direction so as to be opposed to the fixed switching mechanism part 36 a (36 b, 36 c). The central part of the movable switching mechanism part 37 a (37 b, 37 c) contains a movable contact maker configured so as to be enabled to contact to and leave from the fixed contact maker of the fixed switching mechanism part 36 a (36 b, 36 c) in the horizontal direction.

One side of the link mechanism 38 a (38 b, 38 c) is connected mechanically to the movable contact maker of the movable switching mechanism part 37 a (37 b, 37 c) at its opposite side to the fixed switching mechanism part 38 a (38 b, 38 c). The link mechanism 38 a (38 b, 38 c) is formed as a unit of mechanical components coupled mechanically to one another such as insulating rod, revolving shaft lever and operation rod. The other side of the link mechanism 38 a (38 b, 38 c) extends below the base plate 16 a (16 b, 16 c), and is connected mechanically to the manipulator (not shown) for the disconnecting switch, contained in the container box 13.

The fixed contact maker 40 a (40 b, 40 c) of the earthing switch 5 a (5 b, 5 c) is connected electrically to the main circuit conductor 23 a (23 b, 23 c) through the conductive member 39 a (39 b, 39 c). The movable contact maker 41 a (41 b, 41 c) installed so as to be enabled to contact to and leave from the fixed contact maker 40 a (40 b, 40 c) is placed below the fixed contact maker 40 a (40 b, 40 c) in the vertical direction and at the opposed position to the fixed contact maker 40 a (40 b, 40 c). A pair of the fixed contact maker 40 a (40 b, 40 c) and the movable contact maker 41 a (41 b, 41 c) forms the switching part 42 a (42 b, 42 c) of the earthing switch 5 a (5 b, 5 c). The movable contact maker 41 a (41 b, 41 c) is operated by the manipulator (not shown) for the earthing switch contained in the container box 13.

The fixed contact maker 44 a (44 b, 44 c) of the feeding disconnecting switch is connected electrically to the main circuit conductor 23 a (23 b, 23 c) through the conductive member 43 a (43 b, 43 c). The movable contact maker 45 a (45 b, 45 c) installed so as to be enabled to contact to and leave from the fixed contact maker 44 a (44 b, 44 c) is placed below the fixed contact maker 44 a (44 b, 44 c) in the vertical direction and at the opposed position to the fixed contact maker 44 a (44 b, 44 c). A pair of the fixed contact maker 44 a (44 b, 44 c) and the movable contact maker 45 a (45 b, 45 c) forms the switching part 46 a (46 b, 46 c) of the feeding disconnecting switch. The movable contact maker 45 a (45 b, 45 c) is operated by the manipulator (not shown) for the feeding disconnecting switch contained in the container box 13.

The fixed contact maker (not shown) of the earthing switch 3 a (3 b, 3 c) is connected electrically to the main circuit conductor 32 a (32 b, 32 c) through the conductive member (not shown). The movable contact maker (not shown) installed so as to be enabled to contact to and leave from the fixed contact maker is placed below the fixed contact maker in the vertical direction and at the opposed position to the fixed contact maker. A pair of the fixed contact maker and the movable contact maker forms the switching part of the earthing switch 3 a (3 b, 3 c). The movable contact maker is operated by the manipulator (not shown) for the earthig switch contained in the container box 13.

At one side of the ceiling board 19 a (19 b, 19 c) (at the side of the switching part 31 a (31 b, 31 c) of the disconnecting switch 2 a (2 b, 2 c)), the instrumentation transformer 47 a (47 b, 47 c) and the arrester 4 a (4 b, 4 c) are arranged along the line on which the containers 15 a to 15 c are installed. The instrumentation transformer 47 a (47 b, 47 c) and the arrester 4 a (4 b, 4 c) are supported so as to be suspended down from the ceiling board 19 a (19 b, 19 c). The instrumentation transformer 47 a (47 b, 47 c) is used for measuring the circuit voltage of U-phase (V-phase, W-phase) used for operating the switching part 33 a (33 b, 33 c) of the disconnecting switch 2 a (2 b, 2 c), and its primary lead line is connected electrically to the connector 48 a (48 b, 48 c) formed at the main circuit conductor 32 a (32 b, 32 c). The arrester 4 a (4 b, 4 c) is used for regulating the overvoltage to be propagated to the circuit of U-phase (V-phase, W-phase).

The instrumentation transformers 6 a to 6 d are installed at the other side of the ceiling board 19 b (at the side of the breaker part 1 b of the switchgear 1 b). The instrumentation transformers 6 a to 6 d are arranged lengthwise and breadthwise in two columns so as to be suspended from the ceiling board 19 b. The instrumentation transformers 6 a to 6 d are used for measuring the circuit voltage of U-phase to W-phase to be used for operating the breaker part 22 a (22 b, 22 c) of the disconnecting switch 1 a (1 b, 1 c). The instrumentation transformers 6 a to 6 d are composed of the core part having the primary winding and the secondary winding and insulated by the insulating gas or the insulating oil, and four conductive terminals extending down below the core part and insulated by the insulating material such as epoxy resin. Two of four conductive terminals form the primary-side terminals and the rest of the conductive terminals form the secondary-side terminals.

The primary-side lead line 49 connected electrically to one side of the primary-side terminal of the instrumentation transformer 6 a is routed from the inside of the container 15 b through the insulating tube 21 a to the inside of the container 15 a, and is connected electrically to the terminal 52 a installed in the main circuit conductor 23 a. The other side of the primary-side terminal of the instrumentation transformer 6 a and one side of the primary-side terminal of the instrumentation transformer 6 b are connected electrically in series connection. Though not shown in the figure, the primary-side lead line 49 is supported by the insulating support member mounted at the ceiling board 19 a.

The primary-side lead line 51 connected electrically to one side of the primary-side terminal of the instrumentation transformer 6 d is routed from the inside of the container 15 b through the insulating tube 21 b to the inside of the container 15 c, and is connected electrically to the terminal 52 c installed in the main circuit conductor 23 c. The other side of the primary-side terminal of the instrumentation transformer 6 d and one side of the primary-side terminal of the instrumentation transformer 6 c are connected electrically in series connection. Though not shown in the figure, the primary-side lead line 51 is supported by the insulating support member mounted at the ceiling board 19 c.

The primary-side lead line 50 connected electrically to the other side of the primary-side terminal of the instrumentation transformer 6 b and to one side of the primary-side terminal of the instrumentation transformer 6 c is connected electrically to the terminal 52 b installed in the main circuit conductor 23 b. The secondary-side lead line (not shown) connected electrically to the secondary-side terminal of the instrumentation transformers 6 a to 6 d is connected electrically to the instrumentation device.

According to the above described embodiment, as the instrumentation transformers 6 a to 6 d are arranged within the container 15 b which is located in the midst of the center among the containers 15 a to 15 c arranged together, the installation operation of the instrumentation transformers 6 a to 6 d into the containers and the withdrawal operation of the instrumentation transformers 6 a to 6 d from the containers may be applied only to the container 15 b, and the installation and withdrawal operation at the other containers may be done simply by wiring the primary-side lead lines. Owing to this configuration, the work load and work time for the installation operation of the instrumentation transformers 6 a to 6 d into the containers and the withdrawal operation the instrumentation transformers 6 a to 6 d from the containers can be reduced to a large extent, which may lead to an increase in the working efficiency for the installation operation of the instrumentation transformers 6 a to 6 d into the containers and the withdrawal operation the instrumentation transformers 6 a to 6 d from the containers. Thus, the working efficiency for the assembly operation of the switchgear and the replacement operation of the instrumentation transformers 6 a to 6 d can be increased.

The installation operation of the instrumentation transformers 6 a to 6 d into the containers is performed as follows. At first, the instrumentation transformers 6 a to 6 d are made mounted on the ceiling board 19 b. Next, the ceiling board 19 b is made lifted by the crane, and mounted at the side wall 17 b of the container 19 b. Then, the wiring operation for the primary-side lead lines are performed for the containers 15 a to 15 c. The removal operation of the instrumentation transformers 6 a to 6 d from the containers is performed by applying the above installation procedures in reverse order.

According to this embodiment, the primary-side lead line 49 connected electrically to the primary-side terminal of the instrumentation transformer 6 a and the primary-side lead line 51 connected electrically to the primary-side terminal of the instrumentation transformer 6 d can be routed easily from the container 15 b to the containers 15 a and 15 d. In case that the instrumentation transformers are installed within the containers 15 a and 15 c, there occurs such a part that a couple of primary-side lead lines connected electrically to the primary-side of the instrumentation transformer are required to be routed, which leads to increasing the complexity of cable routing or to upsizing the containers. In this embodiment, on the contrary, as the instrumentation transformers 6 a to 6 d are installed within the container 15 b, a single cable routed from the container 15 b to the containers 15 a and 15 c can accommodate the primary-side lead line 49 connected electrically to the primary-side terminal of the instrumentation transformer 6 a and the primary-side lead line 51 connected electrically to the primary-side terminal of the instrumentation transformer 6 d, which leads to reducing the complexity of cable routing or to downsizing the containers. Thus, the economical efficiency of the switchgear can be increased.

According to this embodiment, as the insulating tube 21 a is linked between the container 15 a and the container 15 b and the insulating tube 21 a is linked between the container 15 b and the container 15 c, cyclic currents do not flow among the containers. Owing to this configuration, it will be appreciated that the heat build-up at the containers 15 a to 15 c can be reduced. Thus, the safety of the switchgears can be increased.

FIG. 7 shows a three-phase connection diagram of the switchgear in the second embodiment of the present invention. In this embodiment, the instrumentation transformers 7 a to 7 d are used for measuring the circuit voltage of U-phase to W-phase, and their primary-side is composed with star-connection. The component parts identical to those in the previous embodiment have like numbers and their detail description is not repeated here.

One terminal of the primary side of the instrumentation transformer 7 a is connected electrically to the generator-side of the disconnecting switch 1 a. One terminal of the primary side of the instrumentation transformer 6 c is connected electrically to the generation-side of the disconnecting switch 1 b. one terminal of the primary side of the instrumentation transformer 6 e is connected electrically to the generation-side of the disconnecting switch 1 c.

The other terminal of the primary side of instrumentation transformer 7 a and one terminal of the primary side of the primary side of instrumentation transformer 7 b are connected electrically in series. The other terminal of the primary side of instrumentation transformer 7 c and one terminal of the primary side of the primary side of instrumentation transformer 7 d are connected electrically in series. The other terminal of the primary side of instrumentation transformer 7 e and one terminal of the primary side of the primary side of instrumentation transformer 7 d are connected electrically in series. The other terminal of the primary side of instrumentation transformer 7 b and the other terminal of the primary side of the primary side of instrumentation transformer 7 d, and the other terminal of the primary side of the primary side of instrumentation transformer 7 f are connected electrically in series.

FIG. 5 and FIG. 6 illustrate the structure of the switchgear implemented with the three-phase connection diagram shown in FIG. 7. The component parts identical to those in the previous embodiment have like numbers and their detail description is not repeated here. In this embodiment, as in the previous embodiment, the instrumentation transformers 7 a to 7 f are mounted at the other side (at the breaker part 22 a side of the disconnecting switch 1 a) of the ceiling board 19 b within the container 15 b.

The instrumentation transformers 7 a to 7 f are used for measuring the circuit voltage of U-phase to W-phase to be used for operating the breaker part 22 a (22 b, 22 c) of the disconnecting switch 1 a (1 b, 1 c), and are arranged in two columns lengthwise for the container 15 d and in three columns breadthwise for the container 15 so as to be suspended from the ceiling board 19 b. The instrumentation transformers 7 a to 7 d are composed of the core part having the primary winding and the secondary winding and insulated by the insulating gas or the insulating oil, and two conductive terminals (primary-side terminals) and two secondary-side terminals extending down below the core part and insulated by the insulating material such as epoxy resin.

The primary-side lead line 53 connected electrically to one side of the primary-side terminal of the instrumentation transformer 7 a is routed from the inside of the container 15 b through the insulating tube 21 a to the inside of the container 15 a, and is connected electrically to the terminal 52 a installed in the main circuit conductor 23 a. The other side of the primary-side terminal of the instrumentation transformer 7 a and one side of the primary-side terminal of the instrumentation transformer 7 b are connected electrically in series connection. Though not shown in the figure, the primary-side lead line 53 is supported by the insulating support member mounted at the ceiling board 19 a.

The primary-side lead line 54 connected electrically to one side of the primary-side terminal of the instrumentation transformer 7 c is connected electrically to the terminal 52 b installed in the main circuit conductor 23 b. The other terminal of the primary side of instrumentation transformer 7 c and one terminal of the primary side of the primary side of instrumentation transformer 7 d are connected electrically in series.

The primary-side lead line 55 connected electrically to one side of the primary-side terminal of the instrumentation transformer 7 e is routed from the inside of the container 15 b through the insulating tube 21 b to the inside of the container 15 c, and is connected electrically to the terminal 52 c installed in the main circuit conductor 23 c. The other side of the primary-side terminal of the instrumentation transformer 7 e and one side of the primary-side terminal of the instrumentation transformer 7 f are connected electrically in series connection. Though not shown in the figure, the primary-side lead line 55 is supported by the insulating support member mounted at the ceiling board 19 c.

The other side of the primary-side terminal of the instrumentation transformer 7 b the other side of the primary-side terminal of the instrumentation transformer 7 d and the other side of the primary-side terminal of the instrumentation transformer 7 f are connected electrically in series connection. The secondary-side lead line (not shown) connected electrically to the secondary-side terminal of the instrumentation transformers 6 a to 6 d is connected electrically to the instrumentation device.

According to the above described embodiment, as the instrumentation transformers 7 a to 7 f are arranged within the container 15 b which is in the midst of the center among the container 15 a to 15 c, the working efficiency for the installation operation of the instrumentation transformers 7 a to 7 f into the containers and the withdrawal operation of the instrumentation transformers 7 a to 7 f from the containers maybe increased. Thus, the working efficiency for the assembly operation of the switchgear and the replacement operation of the instrumentation transformers 7 a to 7 f can be increased.

In addition, according to this embodiment, as the instrumentation transformers 7 a to 7 f are installed within the container 15 b, a single cable routed from the container 15 b to the containers 15 a and 15 c can accommodate the primary-side lead line 53 connected electrically to the primary-side terminal of the instrumentation transformer 7 a and the primary-side lead line 55 connected electrically to the primary-side terminal of the instrumentation transformer 6 e, which leads to reducing the complexity of cable routing or to downsizing the containers. Thus, the economical efficiency of the switchgear can be increased.

According to the present invention, as the working load and working time for the installation operation of the instrumentation transformers into the containers and the withdrawal operation of the instrumentation transformers from the containers can be reduced to a large extent, the working efficiency for the installation operation of the instrumentation transformers into the containers and the withdrawal operation of the instrumentation transformers from the containers can be increased. Thus, the working efficiency for the assembly operation of the switchgear and the replacement operation of the instrumentation transformers can be increased. In addition, according to the present invention, as the complexity of cable routing or the upsizing of the containers can be reduced, the economical efficiency of the switchgear can be increased. The routing of the primary-side lead lines of the instrumentation transformers can be accommodated in a single cable independently upon the connection method for the primary-side lead lines of the instrumentation transformers. 

What is claimed is:
 1. A switchgear installed in a main circuit from a power generator to a transformer and structured in a phase-separation configuration, comprising: three containers arranged together; a circuit breaker having a breaker part disconnecting said main circuit electrically and insulated by an insulating gas, said breaker part arranged in each of said three containers, and a manipulator for making contact to and leaving from a contact maker of said breaker part; a plurality of instrumentation transformers for measuring a voltage of said main circuit; a switching part of a disconnecting switch and an earthing switch connected electrically to said main circuit and arranged in each of said three containers; an arrester; said plurality of instrumentation transformers being installed in a container located in a midst among said three containers; an instrumentation transformer measuring a circuit voltage operating the switching part of said disconnecting switch on a side of said switching part of said disconnecting switch, and an arrester restricting an excessive voltage propagating to the circuit being provided in parallel along an alignment direction of said three containers; and said instrumentation transformer and said arrester being supported in a manner suspended from a ceiling plate provided in an upper portion of said container.
 2. A switchgear according to claim 1, wherein a primary-side of said plural instrumentation transformers is configured with an open-delta connection method or a star connection method.
 3. A switchgear according to claim 1, wherein the height of said container located among said three containers is higher than that of two other containers. 